Blue eyes traced back to source

A University of Copenhagen team has identified the gene which around
6-10,000 years ago underwent a genetic mutation in one individual who
eventually gave rise to all blue-eyed people.

Professor Eiberg from the Department of Cellular and Molecular
Medicine began his research in 1996, when he "first implicated the OCA2
gene as being responsible for eye colour", as ScienceDaily puts it.

Over the next decade, he and his colleagues "examined mitochondrial
DNA and compared the eye colour of blue-eyed individuals" in countries
including Denmark, Jordan and Turkey.

Eiberg explained: “Originally, we all had brown eyes. But a genetic
mutation affecting the OCA2 gene in our chromosomes resulted in the
creation of a 'switch', which literally 'turned off' the ability to
produce brown eyes."